Histopathology of carotid body in heroin addiction. Possible chemosensitive impairment

Aims: To perform a morphometric analysis of carotid bodies in opiate addicts. Methods and results: Carotid bodies were sampled at autopsy from 35 subjects who died of heroin intoxication (mean age 26 years), and from eight young (22 years) and eight older subjects (66.5 years) who died of trauma. Sections were stained with haematoxylineosin, azan-Mallory, and double-labelling immunohistochemistry with antineuronal specific enolase and anti-S100, to count type I and type II cells. Interlobular and intralobular connective tissue was increased both in the opiate cases (43.45 ± 6.79%, P < 0.001, and 13.34 ± 5.72%, P < 0.001, respectively) and older cases (46.67 ± 1.65%, P < 0.001, and 9.62 ± 2.11%, P < 0.05, respectively) compared with young cases (33.17 ± 6.41% and 4.33 ± 1.84%, respectively). The percentage of type II cells in the opiate cases (51.6 ± 7.3%, P < 0.001) and in the older controls (49.0 ± 7.2%, P < 0.01) was higher than in the young cases (37.9 ± 3.0%). Among type I cells, the light cell percentage in the opiate cases (65.85 ± 11%, P < 0.001) was reduced with respect to the two control groups (82.8 ± 5.34%, young; 81.62 ± 8.58%, older). Conclusions: The increases in connective tissue and type II cells are similar to findings in ageing and chronic pulmonary disease, and may be ascribed to glomic hypoxia. A direct action of opiates should be taken into account for the decrease in light cells in heroin addiction. The histopathological changes in the carotid body, by impairing chemosensivity, may play a role in the fatal cardiorespiratory derangement of heroin addicts.